1. Field of the Invention
The present invention relates to a circuit for discharging AC power, and more particularly, a circuit for discharging AC power capable of minimizing standby power consumption.
2. Description of the Related Art
Interest in the necessity of saving energy has recently increased around the world, and particularly, the awareness of standby power unintentionally consumed when an electronic apparatus is in a standby state has increased. Standby power refers to power consumed to maintain a computer or a home appliance in a preparatory state prior to the computer or the home appliance being normally operated and also refers to power consumed without being actually used when an electrical plug is inserted into a socket. For example, in the case of a product such as a television or a video player operated by remote control, a remote control receiving state, in which the product is turned off but is ready to be turned on when the remote controller is pressed, corresponds to standby power. The entirety of actual power consumed by electronic devices in the inactive states as described above is commonly estimated to make up about 10% of all consumer electricity charges. Accordingly, the demand for a circuit for reducing the consumption of standby power has increased.
Meanwhile, a capacitor is installed in a power supply terminal of an electronic product, that is, an AC power line, in order to suppress electro-magnetic interference (EMI) therein. Particularly, a capacitor installed in a line-to-line scheme in order to filter differential mode noise is called an X-cap and a capacitor installed in a line-to-ground scheme with respect to each line in order to filter common mode noise is called a Y-cap. Since these capacitors are directly connected to the AC power line, they have a safety standard that should be obeyed. According to the safety standard, when the supply of AC power is blocked, voltage charged in the capacitor needs to be discharged within a predetermined time. In addition, since a discharging resistor is additionally connected in parallel with the capacitor for suppressing the EMI connected to an input terminal of the AC power line, when AC power is supplied, a predetermined amount of standby power has continually been consumed.